Anti-icing agent



United States Patent 3,123,162 ANTI-KIING AGENT Donald A. Maxwell and Ben N. Stuckey, Krngsport,

Tenn, assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Oct. 18, 1961, Ser. No. 145,972 Claims. (Cl. 44-70) This invention relates to additives for reducing ice formation temperature in liquid fuels containing entrained water, and to fuels containing such additives.

A problem with modern aviation fuels, particularly jet engine fuels, has been the formation of ice crystals in the fuel at extremely low temperatures. At low temperatures encountered in high altitude flying, Water entrained even in small amounts in the liquid fuel will form ice crystals which tend to accumulate, restricting fuel lines and fuel tank drains. The temperature at which these crystals begin to form in the fuel is called the ice formation temperature.

An object of this invention therefore, is to provide an additive to inhibit ice formation in aviation fuel at the low temperatures encountered under extreme flying conditions. Broadly an object is to provide an additive for reducing ice formation temperature in hydrocarbon liquids containing entrained water. Particularly an object is to provide an additive which can reduce the ice formation temperature in a water saturated jet engine fuel at least to 65 F., a temperature near the extreme of low temperatures encountered in high altitude flying. Another object is to provide fuels containing these additives.

We have found that the ice formation temperature of water-saturated hydrocarbon liquids, especially jet fuels, can be lowered by addition of a small amount of bis-(3- methyl norcamphane-Z-methylol) azelate to the hydrocarbon liquid.

To be suitable as an additive for depressing the ice formation temperature of jet fuels the material must be able to reduce ice formation temperature to 65 F., without imparting corrosive or other deleterious properties to the fuel and without deleterious effect on its function as a jet fuel. We have found that the additive mentioned above is suitable in these respects when added in small amounts, even in amounts less than 1 volume percent of fuel.

In a preferred embodiment of the invention a jet fuel having an ice formation temperature of 65 F., or lower consists of a jet fuel, for instance JP-4 jet fuel, to which has been added a small amount of bis-(3-methyl norcamphane-Z-mchylol) azelate. While we have been concerned primarily with the problem of reducing ice formation temperature of jet fuels, it is to be understood that the additives of the invention may be added to other liquid hydrocarbon fuels, such as gasoline or diesel fuel to perform the function of reducing ice formation temperature.

To determine the ice formation temperature of fuels We employed the apparatus of ASTM test D97-57 for pour point. The procedure of that test was modified to determine ice formation temperature. The temperature of the sample was reduced to the ice formation temperature, that is, to the temperature at which ice crystal formation was first observed in the fuel sample.

The amount of additive needed will depend upon a number of factors including the desired depression of ice formation temperature, and the characteristics of fuel being treated; the amount will have to be determined for each particular application. For the IP-4 jet fuels we have selected for testing, from 0.10 to 0.25 volume per- 3,128,162 Patented Apr. 7., 1964 "ice cent of the additive of the invention was suflicient to reduce ice formation temperature to -65 F. The following example illustrates the invention by reference to a preferred embodiment.

Example -I A sample of JP-4 jet fuel was saturated with water. The saturated sample contained ppm. plus 2 ml. of water per gallon of fuel. A control portion of this sample was tested by the modified procedure described above to determine ice formation temperature. The temperature was lowered until formation of ice crystals in the sample was observed. This occurred at -54 F. To another portion of the saturated fuel sample was added 0.10 volume percent of bis-(3-methyl norcamphane-2- methylol)azelate. This portion was tested by the same method and the ice formation temperature was found to be 68 F.

Depression of ice formation temperature of JP-4 jet fuels will occur when an amount from about 0.01 to about 0.5 percent by weight of the additive of the invention is added to the fuel. The degree of depression will increase, though not necessarily proportionately, as the amount of additive present is increased within this range. For other fuels the range of effective addition may be greater.

The hydrocarbon liquids contemplated by this invention are those petroleum fractions ordinarily used as fuels in internal combustion piston and jet engines. Such fuels seldom have a distillation end point above 600-650 F. and are low-viscosity liquids unsuitable for lubricant uses. JP-4 jet fuel and some other jet engine fuels among the kind contemplated are described in Military Specification Mil-J-5624D.

The additive of this invention may be prepared by reacting azelaic acid with 3-methyl norcamphane-Z-methylol by conventional esterification methods.

The invention has been described by reference to specific examples, it being understood that variations and modifications can be made within the spirit and scope of the appended claims.

We claim:

1. A hydrocarbon-base fuel comprising a major proportion of hydrocarbon liquid having a distillation end point below 650 F. and from about 0.01 to about 0.5 volume percent, based on the hydrocarbon volume, of bis-(3- methyl norcamphane-Z-methylol) azelate.

2. A hydrocarbon-base fuel consisting essentially of jet engine fuel and from about 0.01 to about 0.50 volume percent of bis-(3-methyl norcamphane-Z-methylol) azeate.

3. A hydrocarbon-base fuel comprising a major proportion of gasoline and from about 0.01 to about 0.5 volume percent, based on the hydrocarbon volume, of bis-(3-methyl norcamphane-Z-methylol) azelate.

4. A hydrocarbon-base fuel comprising a major proportion of diesel fuel and from about 0.01 to about 0.5 volume percent, based on the hydrocarbon volume, of bis-(3-methyl norcamphane-Z-methylol) azelate.

5. A hydrocarbon-base fuel comprising a major proportion of jet fuel and from about 0.01 to about 0.5 volume percent, based on the hydrocarbon volume, of bis-(3-methyl norcamphane-Z-methylol) azelate.

Bell et a1. July 2, 1957 Moore Nov. 22, 1960 

1. A HYDROCARBON-BASE FUEL COMPRISING A MAJOR PROPORTION OF HYDROCARBON LIQUID HAVING A DISTILLATION END POINT BELOW 650*F. AND FROM ABOUT 0.01 TO ABOUT 0.5 VOLUME PERCENT, BASED ON THE HYDROCARBON VOLUME, OF BIS-(3METHYL NORCAMPHANE-2-METHYLOL) AZELATE. 